Doesn't include many accessories. Purists might find the sound a bit bass-heavy, lacking at times in the higher frequencies.

Bottom Line

A little light on accessories for the price, KEF's M400 on-ear headphones offer a high quality, notably bass-forward, audio experience.

KEF recently updated its headphone lineup, with the on-ear M400 among the notable additions. At $249.99, the M400 is priced to compete with some of the more luxurious offerings on the market from Sennheiser and Bowers & Wilkins, and while the headphones may not blow the competition out of the water, they can certainly hold their own. Purists might find the M400 a bit too bass-forward, but this sound signature will appeal to many listeners. More high-frequency presence, and perhaps a more compelling accessory range, given the price, would be appreciated. But overall, the KEF M400 delivers a strong audio performance.

DesignAvailable in black, blue, orange, or white, the lightweight M400's matte finish of brushed metal and leather gives it a sleek, minimalist look. Its supra-aural (on-ear) design feels quite comfortable thanks to ample cushioning in the perforated leather earpads, although the headband lacks much in the way of padding and its rubberized underside can feel like it's pressing on your scalp over long listening periods. A pivoting connection point for the earpads allows for a secure on-ear though it would be nice to see stop points on the headband to allow for precise adjustment. Beneath the earpads, each ear houses a 40mm driver.

An inline remote control (with mic) is situated at roughly chin-height along the detachable cable, which connects to the left earcup. The remote is of the three-button variety, with a multifunction button for playback, track navigation, and call management, and two dedicated buttons for volume control (which work in conjunction with your mobile device's volume). At this price, an extra cable would be nice.

A small cloth zip-up pouch is bundled with the M400—the headphones fold down at joints on the headband to fit inside. Also included: an airline jack adapter, but oddly, no ¼-inch headphone jack adapter for stereo systems and pro gear.

Performance and ConclusionsOn tracks with sub-bass content, like The Knife's "Silent Shout," the M400 delivers robust, deep bass response, and doesn't distort at top listening levels. At moderate volumes, the sense of fullness in the lows is still very much present, though at times on this track, the lows almost seem to overpower the highs slightly.

Bill Callahan's "Drover," a track with less in the way of deep bass, gives us a better idea of the M400's overall sound signature. The drums on this track receive a healthy dose of low-end boosting—not so much that they overpower the mix, but this is certainly a bass-forward sound, which also ends up giving Callahan's baritone vocals some extra—if unnecessary—richness. The guitar strumming on this track could be a tad brighter, but it doesn't sound dulled—it's still fairly crisp and very much part of the mix. Callahan's vocals also receive high-mid edge to help them remain clear and well-defined. Things never sound muddy, but the balance of the sound signature does seem to favor the lows and low-mids.

On Jay-Z and Kanye West's "No Church in the Wild," the kick drum loop's attack gets enough high-mid presence to sound sharp and punchy, but it could benefit from even a little more treble edge, as there's plenty of low and low-mid frequency presence to contend with. The sub-bass synth hits on this track are delivered with depth and power, and the sustain of the drum loop also gets some extra body thanks to the bass-boosted sound of the M400.

On orchestral tracks, like the opening scene in John Adams' The Gospel According to the Other Mary, the M400 keeps the spotlight on the strings, brass, and vocals, all of which retain their brightness. The lower register instrumentation, however, gets plenty of added depth here, bringing it forward in the mix a bit. This may not be a sound that appeals to purists seeking flat response, but those who like a bass depth and richness without things going too far will likely enjoy the M400's overall sound—though a little extra high-mid presence would balance things out a bit more.

In this price range, there are several on-ear options we think offer a great audio experience—the Bowers & Wilkins P5 Series 2, Beyerdynamic T 51 i, and Sennheiser Momentum On-Ear all are strong options with varying degrees of bass and treble balance. If you're looking to spend less money, consider the Marshall Major II, which delivers a solid on-ear audio experience for the price. It's hard to knock the KEF M400 for much other than being a bit light in the accessory department for a $250 pair of headphones. From an audio standpoint, the M400 delivers a bass-forward approach that will appeal to plenty of listeners, and whether you find yourself yearning for a bit more high-mid presence is more a matter of personal listening preference than a comment on the quality of the audio.

KEF M400

KEF M400

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